Max II clutch center to center, belt size and adding HP

[Fxfordguy]

I'm upgrading my 1996 max 2 engine from a briggs 14hp to 23hp Briggs I'm looking for a new belt and need to know the size of the belt and clutch center to center. Does anyone know or know where to find the info? Also do I need to change my clutch springs for the added hp.
Thanks